Downhole jet unit for testing and completing wells

ABSTRACT

The invention relates to pumping engineering, mainly to downhole jet production units. The inventive downhole jet unit comprises a packer, a pipe column and a jet pump. An active nozzle is embodied in the body of the jet pump, and a pass channel provided with a mounting face for a sealing assembly with an axial channel is embodied therein. Said unit is also provided with an irradiator and a receiver transformer of physical fields which are mounted on a cable. The output of the jet pump is connected to a space around the pipe column. The input of a channel for feeding the pumped out medium of the jet pump is connected to the internal space of the pipe column below the sealing assembly. The input of a channel supplying a working medium to the active nozzle is connected to the internal space of the pipe column above the sealing assembly. The invention makes it possible to optimise dimensions of various elements of the unit, thereby increasing the operating reliability of the downhole jet unit.

FIELD OF INVENTION

[0001] This invention relates to the field of pumping engineering,mainly to downhole jet units for production of oil and intensificationof oil inflow from wells.

PRIOR ART

[0002] Known in the art is a downhole jet unit comprising a jet pumpinstalled on the production string in the well and a geophysicalinstrument placed in the production string below the said jet pump (SU1668646 A1).

[0003] The said jet pumping unit enables to pump different extractedmedia, e.g., oil, out of the well with the simultaneous treatment of theextracted medium and the well formation zone, but the arrangement of thejet pump above the sealing assembly sometimes does not enable to makethe channels for supplying the pumped out medium in an optimal relationto the diameter of the channels for supplying the working medium, thus,in some cases, narrowing the field of application of the said unit.

[0004] The closest, as to its technical essence and the achievableresult, to this invention is a downhole jet unit for testing andcompleting wells, which comprises a packer, a piping string and a jetpump, the body of the said pump comprising an active nozzle and a mixingchamber, as axially arranged therein, and a pass channel made with amounting face for installing a sealing assembly with an axial channel,the said downhole jet unit being provided with an irradiator andreceiver-transformer of physical fields, which is arranged on the jetpump side for entry of the medium pumped out of the well and isinstalled on the cable put through the axial channel of the sealingassembly, the output side of the jet pump is connected to the spacesurrounding the piping string, the jet pump channel side for entry ofthe pumped out medium is connected to the inner cavity of the pipingstring below the sealing assembly, and the input side of the channel forsupplying the working medium to the active nozzle is connected to theinner cavity of the piping string above the sealing assembly (RU 2059891C1).

[0005] The said downhole jet unit enables to perform various productionoperations in the well below the jet pump installation level by, interalia, reducing a pressure difference both above and below the sealingassembly. However, the said downhole jet unit does not enable to utilizeits possibilities in full due to non-optimal relationships betweendimensions of various components of the construction of the downhole jetunit.

DISCLOSURE OF INVENTION

[0006] The objective of this invention is to optimize the dimensions ofvarious components of the construction of the downhole jet unit and,owing to it, to raise the reliability of its operation.

[0007] The stated objective is achieved owing to the fact that thedownhole jet unit comprises a packer, a piping string and a jet pump, inthe body of which an active nozzle and a mixing chamber are axiallyarranged, and a pass channel is made with a mounting face for installinga sealing assembly having an axial channel, the said unit being providedwith an irradiator and receiver-transformer of physical fields, which isarranged at the jet pump side for entry of the medium pumped out of thewell and is mounted on the cable put through the axial channel of thesealing assembly, the jet pump output side is connected to the holeclearance, the input side of the channel for supplying the pumped outmedium of the jet pump is connected to the inner cavity of the pipingstring below the sealing assembly, and the input side of the channel forsupplying the working medium to the active nozzle is connected to theinner cavity of the piping string above the sealing assembly, wherein,according to this invention, the diameter of the channel for supplyingthe working medium is not less than the diameter of the mixing chamber,the diameter of the pass channel below the mounting face is, at least,0.8 mm less than its diameter above the mounting face, the diameter ofthe sealing assembly is, at least, 1.6 mm less that the diameter of theinner hole of the tubes, the diameter of the axial channel in thesealing assembly is, at least, 0.009 mm larger than the diameter of thecable, the diameter of the irradiator and receiver-transformer ofphysical fields is, at least, 1.6 mm less that the diameter of the passchannel below the mounting face, the diameter of the pass channel in thepacker is, at least, 1.6 mm larger than the diameter of the irradiatorand receiver-transformer of physical fields, and the irradiator andreceiver-transformer of physical fields is made with the possibility ofits operation in the under-packer zone both when the jet pump is workingand when it is stopped.

[0008] The analysis of the operation of the downhole jet unit has shownthat the its reliability may be increased by making various componentsof the construction of the unit according to strictly defineddimensions. Taking into account that the jet pump capacity mainlydepends on the flow rate of the working medium passing through theactive nozzle, the diameter of the channel for supplying the workingmedium to the active nozzle has been selected as the typical dimension.It has been found out in this connection that it is not advisable tomake the diameter of the said channel less that the diameter of themixing chamber. As to the upper limit, it should be defined by thestrength characteristics of the jet pump construction, and, first ofall, by those of the jet pump body, as well as by the required maximumcapacity, which is necessary for pumping the medium out of the well. Ineach particular case this value is to be determined individually. In thecourse of the unit operation studies of different well modes areconducted. One has to install and remove the sealing assembly, and move,in the process of operation, the irradiator and receiver-transformer ofphysical fields along the well. It has been determined that it is notadvisable to make the diameter of the pass channel below the mountingface of the sealing assembly that it would be less than 0.8 mm less thanthe diameter of the inner hole of the piping string, and the diameter ofthe sealing assembly itself should be made at least 1.6 mm less than thediameter of inner hole of the piping string. In the result, possiblesticking of the sealing assembly in the piping string duringinstallation or removal of the sealing assembly is precluded, and thereliable installation of the sealing assembly onto the mounting face isensured. It has already been said that in the process of the unitoperation it is necessary to move the irradiator andreceiver-transformer of physical fields along the well and, at the sametime, minimize the medium flow through the axial channel of the sealingassembly. It has been achieved by making the irradiator andreceiver-transformer of physical fields at least 1.6 mm less than thediameter of the packer pass channel and the diameter of the pass channelbelow the sealing assembly mounting face, and the diameter of the axialchannel in the sealing assembly should be made that it would be at least0.009 mm larger than the diameter of the cable, on which the irradiatorand receiver-transformer of physical fields is installed. Finally, theabove-indicated relationships of dimensions enable to arrange theirradiator and receiver-transformer of physical fields in theunder-packer zone both when the jet pump is working and when the jetpump is stopped. It enables to expand the range of studies carried outin wells, which is of special importance when carrying restorationworks.

[0009] Thus, the objective of the invention—to optimize the dimensionsof various components of the construction of the unit and, owing to it,raise the reliability of operation of the downhole jet unit—has beenachieved.

BRIEF DESCRIPTION OF DRAWINGS

[0010]FIG. 1 represents a longitudinal section of the disclosed downholejet unit.

[0011]FIG. 2 represents a longitudinal section of the sealing assembly.

BEST EMBODIMENT OF THE INVENTION

[0012] The downhole jet unit for testing and completing wells comprisesa packer 1, a piping string 2, and a jet pump 3, in the body 4 of whichan active nozzle 5 and a mixing chamber 6 are axially arranged, and apass channel 7 is made with a mounting face 8 for installing a sealingassembly 9 having an axial channel 10. The unit is also provided with anirradiator and receiver-transformer 11 of physical fields, which isarranged at the side of the jet pump 3 for entry of the medium pumpedout of the well and is mounted on the cable 12 put through the axialchannel 10 of the sealing assembly 9. The output side of the jet pump 3is connected to the space surrounding the piping string 2. The inputside of the channel 13 for supplying the pumped out medium of the jetpump 3 is connected to the inner cavity of the piping string 2 below thesealing assembly 9, and the input side of the channel 14 for supplyingthe working medium to the active nozzle 5 is connected to the innercavity of the piping string 2 above the sealing assembly 9. The diameterD₇ of the channel 14 for supplying the working medium is not less thanthe diameter D₈ of the mixing chamber. The diameter D₆ of the passchannel 7 below the mounting face 8 is, at least, 0.8 mm less than itsdiameter D₃ above the mounting face 8. The diameter D₄ of the sealingassembly 9 is, at least, 1.6 mm less that the diameter D₁ of the innerhole of the tubes 2. The diameter D₅ of the axial channel 10 in thesealing assembly 9 is, at least, 0.009 mm larger than the diameter D₂ ofthe cable 12. The diameter D₁₀ of the irradiator andreceiver-transformer 11 of physical fields is, at least, 1.6 mm lessthat the diameter D₆ of the pass channel 7 below the mounting face 8.The diameter D₉ of the pass channel 15 in the packer 1 is, at least, 1.6mm larger than the diameter D₁₀ of the irradiator andreceiver-transformer of physical fields, and the irradiator andreceiver-transformer 11 of physical fields is made with the possibilityof operating in the under-packer zone both when the jet pump 3 isoperating and when it is stopped.

[0013] The jet pump 3 and the packer 1 on the piping string 2 arelowered into the well and are placed above the producing formation. Thepacker 1 is brought into the operating position, thus separating thespace surrounding the piping string in the well. The sealing assembly 9and the irradiator and receiver-transformer 11 of physical fields arelowered on the cable 12. Via the piping string 2 a working medium, e.g.,water, salt solution, oil, etc., is pumped. The working medium comesfrom the piping string through the channel 14 into the active nozzle 5of the jet pump 3. Within a few seconds after the pumping of the workingmedium through the active nozzle 5 a stable jet is formed at the nozzleoutput, which, going out of the nozzle 5, entrains the surroundingmedium into the jet pump, which results in a pressure reduction first inthe channels 13 for supplying the pumped out medium and then in theunder-packer space of the well, thus creating pressure drawdown onto theproducing formation. The amount, for which the pressure is lowered,depends on the rate, at which the working medium goes through the activenozzle 5, which rate, in its turn, depends on the pressure value of theworking medium discharged into the piping string 2 above the sealingassembly 9. In the result, the formation medium comes over the sectionof the piping string 2 below the sealing assembly 9 and goes through thechannels 13 into the jet pump 3, where it is mixed with the workingmedium, and the mixture of the media, owing to the energy of the workingmedium comes over the borehole clearance of the piping string 2 out ofthe well and on the surface. During the pumping out of the formationmedium the parameters of the pumped out formation medium are monitored,and the formation medium is influenced with the irradiator andreceiver-transformer 11 of physical fields. Depending on a particulartask it is possible to move the irradiator and receiver-transformer 11of physical fields along the well, including the arrangement of theirradiator and receiver-transformer 11 of physical fields in theunder-packer zone at the level of the producing formation.

Industrial Applicability

[0014] This invention may be applied when testing, completing andoperating oil or gas condensate wells as well as when conductingworkover jobs thereon.

What is claimed, is:
 1. The downhole jet unit for testing and completingwells, comprising a packer, a piping string and a jet pump, in the bodyof which an active nozzle and a mixing chamber are axially arranged, anda pass channel is made with a mounting face for installing a sealingassembly having an axial channel, said unit being provided with anirradiator and receiver-transformer of physical fields, which isarranged at the jet pump side for entry of the medium pumped out of thewell and is mounted on the cable put through the axial channel of thesealing assembly, the jet pump output side is connected to the spacesurrounding the piping string, the input side of the channel forsupplying the pumped out medium of the jet pump is connected to theinner cavity of the piping string below the sealing assembly, and theinput side of the channel for supplying the working medium to the activenozzle is connected to the inner cavity of the piping string above thesealing assembly, wherein the diameter of the channel for supplying theworking medium is not less than the diameter of the mixing chamber, thediameter of the pass channel below the mounting face is, at least, 0.8mm less than its diameter above the mounting face, the diameter of thesealing assembly is, at least, 1.6 mm less that the diameter of theinner hole of the tubes, the diameter of the axial channel in thesealing assembly is, at least, 0.009 mm larger than the diameter of thecable, the diameter of the irradiator and receiver-transformer ofphysical fields is, at least, 1.6 mm less that the diameter of the passchannel below the mounting face, the diameter of the pass channel in thepacker is, at least, 1.6 mm larger than the diameter of the irradiatorand receiver-transformer of physical fields, and the irradiator andreceiver-transformer of physical fields is made with the possibility ofoperating in the under-packer zone both when the jet pump is operatingand when it is stopped.